ESR Lab Activity

Introduction

We are going to collect an ESR spectrum from a series of substituted hydroquinones.

Name	SDS	Molar Mass	Sigma Product Number	Cost
A = Hydroquinone (aka. 1,4-benzohydroquinone)	SDS	110.11 g/mol	H9003	22.90 / 100g
B = Methylhydroquinone	SDS	124.14 g/mol	112968	59.20 / 250g
C = 2,3-dimethylhydroquinone	SDS	138.16 g/mol	300756	118.00 / 5g

Solution A: 1 M NaOH; 1 gram NaOH (39.997 g/mol) into 25 mL EtOH.
Solution B: 1 M hydroquinone solution.
Procedure: To 2 ml of 1 M hydroquinone solution add 2-3 drops of solution A. A color change will indicate the reaction has occurred. Quickly transfer colored sample to ESR sample tube, place in ESR spectrometer, tune, and collected data.

Double Syringe Drive

This is the EPR spectrum of the "hydro-semiquinone" (aka. 1,4-benzosemiquinone)

EPR Parameters: 9.4 GHz, 3360 G Center field, 15 G sweep width. [Above data needs the x-axis changed over to magnetic field in G]

This is the EPR spectrum of the "methyl-hydro-semiquinone" (aka. methyl-semiquinone)

EPR Parameters: 9.4 GHz, 3360 G Center field, 15 G sweep width. [Above data needs the x-axis changed over to magnetic field in G]

Hydrosemiquinone EPR spectrum (black) vs Winsim spectrum (red)